Fibromuscular dysplasia (FMD) was first observed in 1938 by Leadbetter and Burkland in a 5-year-old boy, and described as a disease of the renal arteries. Involvement of the craniocervical arteries was recognized in 1946 by Palubinskas and Ripley.
FMD is an angiopathy that affects medium-sized arteries predominantly in young women of childbearing age. FMD most commonly affects the renal arteries and can cause refractory renovascular hypertension. Of patients with identified FMD, renal involvement occurs in 60-75%, cerebrovascular involvement occurs in 25-30%, visceral involvement occurs in 9%, and arteries of the limbs are affected in about 5%. [1, 2] Case reports have shown FMD in most other medium-to-large arteries as well, including the coronary arteries [3] , the pulmonary arteries [4] , and the aorta [5] . In 26% of patients, disease is found in more than one arterial region [6] .
In patients with identified cephalic FMD, 95% have internal carotid artery involvement and 12-43% have vertebral artery involvement. Although FMD can affect arteries of any size [7] , involvement of smaller ones, including intracranial vessels, is rare. Although an early autopsy series of 819 consecutive patients found the prevalence of FMD in the internal carotid arteries to be 1% [8] , a larger, more recent autopsy series of 20,244 patients recently identified the overall prevalence of FMD of the internal carotid arteries to be only 0.02% [9] . From a neurologic perspective, FMD is an important cause of stroke in young adults.
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Digital subtraction angiogram of the right internal carotid artery demonstrates an irregular extracranial portion that is consistent with FMD.
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Conventional angiogram of the left carotid artery demonstrates a 1.5-cm, long, smooth, severe stenosis of the extracranial internal carotid artery. Note that the artery is not completely occluded and a thin continuous string of contrast is present along the length of the stenosis. This smooth tubular stenosis is suggestive of the intimal fibroplasia form of FMD but can be observed with any of the subtypes.
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Cerebral angiogram of the left carotid artery territory demonstrates a long, irregular stenosis with a string-of-beads appearance along the entire extracranial length of the internal carotid artery (ICA). This is consistent with the most common medial dysplasia form of fibromuscular dysplasia. Also note similar involvement of the first 3 cm of the external carotid artery (ECA). Such extensive ICA involvement, as well as ECA involvement, is atypical. Note sparing of the carotid bulb.
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Lateral view of a right carotid angiogram demonstrates multiple stenoses of FMD of the internal carotid artery. The string of beads appearance is suggestive of the medial dysplasia form of FMD.
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Anteroposterior view of a right carotid angiogram demonstrates FMD of the extracranial portion of the right internal carotid artery.
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Angiogram of the descending aorta demonstrates the stenoses of FMD in the renal arteries bilaterally.
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Angiogram of the right vertebral artery demonstrating irregular stenoses of fibromuscular dysplasia at the level of C2-3.
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Illustration of the operative approach of graduated dilatation of the internal carotid artery (ICA). The common carotid and external carotid arteries are cross-clamped, and the superior thyroid artery is clipped while the ICA is isolated, opened, and dilated with progressively larger dilators. This technique has been shown to be successful in the management of medically refractive FMD stenoses.
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Illustration depicts the intraluminal appearance of graduated dilatation of the stenoses of FMD. The dilator is passed into the vessel and opens the bandlike narrowings.
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Illustration depicts the locations of FMD lesions, which differentiate regions with typical and atypical angiographic appearances of this disease.
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Digital subtraction angiography of the left internal carotid artery distribution demonstrates a large 1.5-cm-diameter aneurysm of the right anterior communicating artery. Aneurysms may be associated with systemic vasculopathies such as FMD.
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Small infarct in woman with fibromuscular dysplasia from dissected vertebral artery. An incidental aneurysm, or ovoid diverticula, is noted in the supraclinoid left internal carotid artery.
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Small infarct in woman with fibromuscular dysplasia from dissected vertebral artery. An incidental aneurysm, or ovoid diverticula, is noted in the supraclinoid left internal carotid artery. Dissected vertebral artery.
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Small infarct in woman with fibromuscular dysplasia from dissected vertebral artery. An incidental aneurysm, or ovoid diverticula, is noted in the supraclinoid left internal carotid artery. Internal carotid angiogram.
